不分裂卷积完全匹配层与旋转交错网格有限差分在孔隙弹性介质模拟中的应用

Finite difference modeling of Biot's poroelastic equations with unsplit convolutional PML and rotated staggered grid

完全匹配层吸收边界在地震波模拟中已广泛使用,但常用的场分裂格式完全匹配层吸收边界(SPML)和传统的不分裂完全匹配层吸收边界(NPML)对极低频入射波或大角度入射波的边界吸收效果不好.一种无需分裂和显式卷积计算的完全匹配层吸收边界(CPML)不仅能够解决常规PML吸收边界的不足,而且具有存储量小、计算效率高、易于编程实现的特点.本文将这种完全匹配层(CPML)吸收边界引入到孔隙弹性介质速度应力格式的旋转交错网格有限差分算法中,对完全匹配层吸收边界参数进行数值分析,得到一组优化的参数.孔隙弹性介质数值模拟结果表明这种不分裂卷积完全匹配层的吸收效果优于常规完全匹配层.

Perfectly matched layer （PML） absorbing boundary has been widely used in seismic simulation. At grazing incidence and low frequency, the classical split PML （SPML） method and the traditional nonsplit PML （NPML） method suffer from large spurious reflections. An unsplit convolutional PML （CPML） not only fixes the disadvantages of conventional PML, but also needs less memory, computes efficiently and is easy to program. In this paper, this CPML absorbing boundary is imported to the rotated grid finite-difference method, in velocity-stress formulation, of poroelastic media. The numerical analysis of parameters in the PML absorbing boundary gives a set of optimum parameters. Numerical test shows that the CPML absorbing boundary gives a better result than the conventional PML absorbing boundary.